For a diesel engine-powered vehicle, it is useful to supply the engine with fuel having a precise amount of fuel additives for improving one or more performance characteristics of the vehicle. For example, it is often desirable to supply a diesel engine with an additive that improves the environmental performance of the vehicle. Typically, the additives are mixed with fuel during the fuel production process in an oil refinery. But it is increasingly desirable to provide a vehicle with a fuel delivery system having an on-board fuel additive system. Such an additive system permits a particular vehicle to have its own customized composition of fuel additives, and enables a measured quantity of the fuel additive to be introduced into the fuel tank, such as in response to a quantity of fuel being added to the fuel tank.
Unfortunately, many current fuel additive systems are unnecessarily complex, not easily serviceable, and/or may provide erratic dosing. For example, some fuel additive systems include additive tanks having electric pumps mounted therein, filler caps, vents, pressure relief valves, and complex mounting arrangements. Other additive systems are mounted inside the fuel tank and either cannot be removed for servicing or require removal of the entire fuel tank from the vehicle. Still other additive systems provide additive dosing based predominantly on estimates of pressure by way of temperature measurements. In conclusion, such additive systems may be somewhat unreliable in dosing accuracy, and complicated in design and time-consuming to service and, thus, unnecessarily expensive to buy and maintain.